Electronic circuit for frequency conversion



Dec. 29, 1942. H. E. BROWN 2,306,378

ELECTRONIC CIRCUIT FOR FREQUENGY'CONVERSION Filed Dec. 27, 1940INVENTOR. Hue/1 5. BROWN.

A FOR/V573.

Patented Dec. 29, 1942 ELECTRONIC CIRCUIT FOR FREQUENCY CONVERSION HughE. Brown, Cleveland Heights, Ohio, assignor to The W. S. Tyler CompanyApplication December 27, 1940, Serial No. 371,857

3 Claims.

This invention relates, as indicated, to an electronic circuit forfrequency conversion, but has reference more particularly to a circuitof this character which is especially adapted for controlling thevibrations of industrial vibrating machinery, such as vibrating screensand the like. The invention, further constitutes an improvement over mycopending application, Serial No. 357,749, filed September 21, 1940.

A primary object of the invention is to provide a circuit of thecharacter described which will convert alternating current of acommercial frequency, i. e., 60 cycles, into current of a lowerfrequency, as for example 15 cycles, which is desirable for use invibrating screens and the like.

Another object of the invention is to provide a circuit of the characterdescribed which is characterized by the absence of batteries and ofparts which are subject to breakage or are likely to cause difficulty intheir operation.

A further object of the invention is to provide a circuit of thecharacter described, which embodies a minimum number of tubes, and makesuse of standard tubes which are readily available in the market atfairly low cost.

To the accomplishment of the foregoing and related ends, said invention,then, consists of the means hereinafter fully pointed out in the claims;the annexed drawing and the following description setting forth indetail certain means for carrying out the invention, such disclosedmeans illustrating, however, but one of various ways in which theprinciple of the invention may be used.

In said annexed drawing:

Fig. 1 is a schematic diagram of an electrical circuit embodying thenovel feature of the invention, and

Fig. 2 is an oscillogram of the voltage waves supplied to the load inthe circuit illustrated in Fig. 1.

Referring more particularly to the drawing, the circuit includes asource of alternating current of ordinary public utility voltage, i. e.,220 volts, as represented by the power lines I and 2. A load L is placedin a line 3 which extends from the power line 2. Such load may be themagnet of a vibratory screen, or other load of an inductive character.

The various branches of the circuit are supplied with current by meansof a power transformer I, the primary coil 5 of which is connected tothe supply lines I and 2, and the secondary of which consists of threecoils 6, I and 8. The coil 6 supplies 60 volts at 250 milli-amperes, andthe coil 8 supplies 2 volts at 22 amperes where the power tube to bepresently described is a C6J tube, and 5 volts at 11 amperes where thepower tube is a thyratron power tube.

The main portion of the circuit comprises the line 3, load L, a powertube 9, and a line I0, which connects the cathode I I of the tube 9 withthe supply line I. The anode or plate I2 of the tube 9 is connected tothe line 3. The cathode II is indirectly heated by current supplied bythe coil 8 through wires I3 and I4. The tube 9 is a power tube of theC6J type or a thyratron, and

includes, in addition to the elements II and I2, a grid I5. This portionof the circuit, in the absence of other parts to be presently describedwould produce rectified current impulses, as designated by the positiveimpulses A, C, E, G, J, et seq. in Fig. 2, the negative impulses B, D,F, H, et seq. being omitted.

In order to produce 1800 impulses per minute, it is necessary to somodify the action of the aforesaid portion of the circuit as to omit, inaddition to the negative impulses B, D, F, H, et seq., the alternatepositive impulses C, G, so as to produce for the operation of the loadL, only the impulses, A, E, J, etc. For this purpose, a circuit isemployed which comprises as its principal parts a #56 triode I6, a smallaudio-transformer I! having a 4 to 1 or 5 to 1 ratio, a 2 mid. 800 voltpaper condenser I8, a 4000 ohm 10 watt resistor IS, a .5 mid. 600 voltpaper condenser 20, and a 5000 watt 50 ohm resistor 20'.

The triode I6, consists of a cathode 2|, a grid 22 and an anode or plate23. The plate 23 is connected to the plate terminal P of the transformerby means of a connection 24, and the grid 22 is connected to the gridterminal G of the transformer through a connection 25. The condenser I8is connected across the B plus terminal B and the filament terminal F ofthe transformer. The coil 6 of the power transformer is connected to theterminal B by means of a wire 26 and to the cathode 2I by means of awire 21. A connection between the wire 21 and the terminal F is made bymeans of Wires 29 and 30. The cathode 2| is indirectly heated by thecoil I through wires 3| and 32. The grid 22 is connected to the grid I5through a wire 33 and the resistor 20', the condenser 20 and. resistorI9 being connected in series across the lines 33 and 29.

The aforesaid circuit sets up an oscillatory current which yieldsimpulses which, when transmitted to the grid I5 of the power tube, willcontrol passage of current through said tube.

With the parts as described, and connected together in the mannerdescribed, the power tube 8 will send 1800 impulses per minute throughthe load L.

By changing the size of the transformer I! and the condenser I 8,frequencies other than that which has been described can be obtained. Byusing a larger transformer and a higher capacity condenser, it ispossible to obtain very low frequency effects. I have been able, inpractice, to obtain in this way one impulse per second.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the means andsteps herein disclosed, provided those stated by any of the followingclaims or their equivalent be employed.

I therefore particularly point out and distinct-,

ly claim as my invention:

1. An electron tube control circuit including a source of alternatingcurrent, a load circuit connected across said source and including anelectron tube having plate, cathode and grid elec trodes, meansconnecting the plate-cathode circuit of the tube in series with saidload circuit, and control means for said tube including an oscillationnetwork comprising an electron tube oscillator having plate, cathode andgrid electrodes, means for connecting the cathodes of said tubestogether, means connecting the grid electrodes of the tubes together, anaudio frequency transformer including two windings, means connecting onewinding thereof in series with the plate-cathode circuit of theoscillator tube, means connecting the other Winding of said transformerin series with the grid-cathode circuit of the oscillator tube, one endof each of said windings being connected to the cathode of saidoscillator tube, a condenser connecting the cathode-connected ends ofsaid windings and means for energizing the plate-cathode circuits ofsaid tubes and the cathodes of said tubes from said alternating currentsource.

2. An electron tube control circuit including a source of alternatingcurrent, a load circuit connected across said source and including anelectron tube having plate, cathode and grid electrodes, meansconnecting the plate-cathode circult of the tube in series with saidload circuit,

and control means for said tube including an oscillation networkcomprising an electron tube oscillator having plate, cathode and gridelectrodes, means connecting the cathodes of said tubes together, meansconnecting the grid electrodes of the tubes together, an inductance unithaving a plurality of coils, means connecting a first coil of said unitin series with the platecathode circuit of said oscillator tube, meansconnecting a second coil of said unit in series with the grid-cathodecircuit of the oscillator tube, one end of each of said first and secondcoils being connected to the cathode of said oscillator tube, acondenser connecting the cathode-connected ends of said coils, heatingmeans for the cathodes of said tubes, and means for energizing saidheating means and the platecathode circuits of said tubes from saidalternating current source.

3. An electron tube control circuit including a source of alternatingcurrent, a load circuit connected across said source and including anelectron tube having plate, cathode and grid electrodes, meansconnecting the plate-cathode circuit of the tube in series with saidload circuit, and control means for said tube including an oscillationnetwork comprising an electron tube oscillator having plate, cathode andgrid electrodes, means connecting the cathodes of said tubes together,means connecting the grid electrodes of the tubes together, an iron coreinductance unit having a plurality of coils, means connecting a firstcoil of said unit in series with the plate-cathode circuit of saidoscillator tube, means connecting a second coil of said unit in serieswith the grid-cathode circuit of the oscillator tube, one end of each ofsaid first and second coils being connected to the cathode of saidoscillator tube, a condenser shunted across the cathode-connected endsof said coils, a series connected resistor and condenser forming a shuntconnection between the connected cathodes and grid electrodes of thetubes, heating means for the cathodes of said tubes, and means forenergizing said heating means and the platecathode circuits of saidtubes from said alternating current source.

HUGH E. BROWN.

